Compositions for the oxidative dyeing of hair comprise primary intermediates (such as p-phenylenediamine, p-toluenediamine, p-aminophenol, 4-amino-3-methylphenol) and couplers (such as resorcinol, 2-methylresorcinol, 3-aminophenol, 5-amino-2-methylphenol). A majority of shades have been produced with dyes based on p-phenylenediamine. However, as noted in U.S. Pat. Nos. 5,599,353 and 5,538,516, the use of p-phenylenediamine is being questioned for toxicological reasons, mainly due to its sensitization potential.
Because of the supposed toxicological issues attendant to its use, the art has been looking for substitutes for p-phenylenediamine.
EP 400,330 B1 (GB 2,239,265 A) describes the use of 2-(2-hydroxyethyl)-p-phenylenediamine as a replacement for p-phenylenediamine.
Pyrimidine derivatives, such as tetraaminopyrimidine, have been also suggested as alternatives to p-phenylenediamine (see U.S. Pat. No. Re. 30,199 [U.S. Pat. No. 4,003,699]). However, GB 2,239,265 A, points out that although the use of pyrimidine derivatives as developers has reduced toxicological problems, the pyrimidine derivatives are not completely satisfactory with respect to coloring performance.
U.S. Pat. No. 5,421,833 discloses hair dye compositions asserted to be without sensitizing potential. The dye compositions are disclosed to possess improved dyeing properties for all shades. The compositions comprise only 2-(2'-hydroxyethyl)amino-5-aminotoluene in combination with the usual coupling agents (with the exclusion of 1-methoxy-2,4-diaminobenzene and 1-ethoxy-2,4-diaminobenzene).
The object of the present invention was to develop a p-phenylenediamine alternative having less sensitization potential. This proved to be a difficult task. Since the structure-sensitization relationship is not known, it is difficult to predict whether a hair dye molecule will exhibit much lower potential for sensitization than p-phenylenediamine. Surprisingly and unexpectedly, we have found that 1-(2,5-diaminophenyl)ethylene glycol is a much weaker sensitizer than p-phenylenediamine.